Old PSU as benchtop power

Yeah, that's fine, just remember the following:

1) The power supply may require a load to operate correctly (although that was only definitely true of older power supplies)
2) The power supply is capable of producing a lot of power and is not current limited in a practical sense for breadboarding.
3) the output voltage may be mains ground referenced (so you can't (say) connect two in series to get a higher voltage)

I have found PC power supplies to be quite tolerant of abuse, and the price is often very right (if you can't get one free you're not trying hard enough )

 

Also on most PC PSU's the Green = PS_ON# (turn DC on by shorting to ground) for the PSU to operate
here's an article on converting a PC PSU into a multi output benchtop PSU

http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

cheers
Dave

 

yup my mistake now edited

Dave

 

It's not going to do much good in most cases. It will likely drop the voltage somewhat and be far too slow to react to save a delicate component.

It's not impossible to add a current limit to a PC power supply, however because the internals are at mains potential and there's not much room to fit stuff, it's not what I would recommend -- especially for a beginner.

Taking care is better.

Maybe as a first project you can design something.

Or you could buy something like this. you can power it from the 12V from the PC power supply and the regulators sound like they are current limited to well under 1A. It doesn't help for higher voltages though.

 

Fair enough.

What do you mean by "intermittent multimeter reading"?

 

its varying between xx.97 and xx.99 ... ie its 0.02 of a volt. ?
that could easily be within the counting accuracy of the meter
and nothing to do with what is being read

Dave